The weird edge cases that live around connectors never cease to amaze. I recall one, I think it was also HDMI (maybe displayport or VGA), that showed there's a very low resolution digital graphic or text signal and some connectors even have a screen embedded in them.
>> A photo revealed the chip was a NX3303X; I could not find any datasheets<p>Not much information out there but these are similar chips, possibly it’s a clone?<p>Capstone CS5213 datasheet:<p><a href="https://file.elecfans.com/web2/M00/2B/BD/pYYBAGHVUbyARd_-AAUlwDi2zaY567.pdf" rel="nofollow">https://file.elecfans.com/web2/M00/2B/BD/pYYBAGHVUbyARd_-AAU...</a><p>And also the AlgolTek AG6200 / AG6201 Series, datasheet:<p><a href="https://assets.yoreparo.com/attachments/28SGHqLW2Z2MfSzEBJB47fXQEL9xgipSkHMEkaZz.pdf" rel="nofollow">https://assets.yoreparo.com/attachments/28SGHqLW2Z2MfSzEBJB4...</a>
The CS5213 appears pinout-compatible with the MX929x, interesting. The AG620x is a chip I've had the misfortune of encountering; it was common in Amazon DACs, dropped signal output every 15 minutes or so unless you disconnected the EDID pins from the (monitor?), and interprets input signal in a cursed fashion where 16 or below produces black but only 255 produces full white. If your computer outputs limited range HDMI the analog signal can't reach white, but if your computer outputs full range HDMI the shadows are clipped. This is one of the chips that gave HDMI DACs a reputation for black crush and caused CRT communities to recommend DP.<p>Interestingly the MiSTer game system community actually patched their FPGAs to output digital signals from 16-255, and have some other way of avoiding the signal dropouts (never talk to EDID?), so this chipset is almost <i>seeked out</i> over incompatible models.
These chips appear to be 8051s with multi hundred MHz DACs.<p>Be fun to program them but I can’t find any programmable devboards with the Capstone CS5213.
What kind of mixer do you use?<p>If it has balanced xlr inputs a DI will completely eliminate the earth hum. That the signal is dropped to mic level doesn’t matter much as the impedance is correct, the connection balanced and the mixer preamp designed for the purpose. // I am somewhat professional sound tech :)
3.5mm, I now know why conventional consumer audio devices don't use mixers, they're a ground loop party<p>It's also that I don't know <i>how</i> to build a differential input not limited to power supply range, I do think they are sold and I have a mixer at home but it's somewhat bulky for my computer desks.
I love it when people go so far into the weeds to solve a problem on their own and then document the process for everyone.<p>I learned a lot from this writeup, and really enjoyed the read even though I know I would have made it about 10% of the way myself and chickened out and just bought a different product in hopes it would solve the problem.